How to remediate – Woppoware PostMaster <= 4.2.2 Multiple Vulnerabilities

1. Introduction

Woppoware PostMaster versions up to and including 4.2.2 contain multiple vulnerabilities that could allow an attacker to bypass authentication, disclose information, and execute cross-site scripting attacks. This impacts businesses running webmail services as it allows unauthorised access to user accounts and data. Confidentiality, integrity, and availability may be compromised if exploited successfully.

2. Technical Explanation

Woppoware PostMaster suffers from several flaws including an authentication bypass due to insufficient input validation on the ’email’ parameter of the ‘message.htm’ page. The application also fails to properly sanitise user-supplied data in the ‘wmm’ parameter, leading to potential directory traversal and information disclosure. Finally, malicious input is not filtered from the ‘email’ parameter allowing cross-site scripting attacks. CVE-2005-1650 details the authentication bypass vulnerability.

• Root cause: Missing or inadequate input validation on the ’email’ and ‘wmm’ parameters of the ‘message.htm’ page, leading to insecure handling of user supplied data.
• Exploit mechanism: An attacker can supply a username to the ‘email’ parameter in ‘message.htm’ to bypass authentication. They can then read messages or compose new ones as that user. Directory traversal is possible by manipulating the ‘wmm’ parameter. Cross-site scripting attacks are achieved via injecting malicious code into the ’email’ parameter.
• Scope: Woppoware PostMaster versions 4.2.2 and earlier are affected.

3. Detection and Assessment

Confirming vulnerability requires checking the version of PostMaster running on your system, and testing for authentication bypass.

• Quick checks: Check the Woppoware PostMaster banner page when logged in to the webmail interface.
• Scanning: Nessus plugin ID 28496 may detect this vulnerability as an example only.
• Logs and evidence: Examine web server logs for requests accessing ‘message.htm’ with unusual parameters or attempts to access files outside of expected directories.

curl -I http://your-postmaster-server/message.htm

4. Solution / Remediation Steps

The recommended solution is to disable the webmail service in Woppoware PostMaster, as this removes the attack surface.

4.1 Preparation

• Consider a change window for this activity, especially in production environments. Approval from the IT security team may be needed.

4.2 Implementation

1. Step 1: Access the Woppoware PostMaster administration interface.
2. Step 2: Locate the webmail service configuration settings.
3. Step 3: Disable the webmail service.
4. Step 4: Save the changes and restart the Woppoware PostMaster service if required.

4.3 Config or Code Example

Before

Webmail Enabled: Yes

After

Webmail Enabled: No

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this type of vulnerability. Least privilege reduces the impact if an attacker gains access. Input validation prevents malicious data from being processed. Safe defaults minimise the attack surface by disabling unnecessary features.

• Practice 1: Implement least privilege principles to limit user and service account permissions.
• Practice 2: Enforce strict input validation on all user-supplied data, especially in web applications.

4.5 Automation (Optional)

Automation is not directly applicable for this vulnerability due to the configuration change required.

5. Verification / Validation

Confirm that disabling the webmail service has removed access and that attempts to reach the ‘message.htm’ page are blocked.

• Post-fix check: Attempt to access the webmail interface via a browser; it should be unavailable or redirect to an error page.
• Re-test: Repeat the quick check from section 3, confirming that the banner page is no longer accessible.
• Smoke test: Verify other PostMaster functions (e.g., email sending/receiving) continue to operate as expected.
• Monitoring: Monitor web server logs for failed access attempts to ‘message.htm’ or related webmail paths.

curl -I http://your-postmaster-server/message.htm

6. Preventive Measures and Monitoring

• Baselines: Update your security baseline to reflect disabling unused features like the webmail service in Woppoware PostMaster.
• Asset and patch process: Review configurations regularly, at least monthly, to ensure compliance with security standards.

7. Risks, Side Effects, and Roll Back

Disabling the webmail service will prevent users from accessing their email via a browser interface. Users may need to use an alternative email client. To roll back, re-enable the webmail service in the Woppoware PostMaster administration interface and restart the service.

• Risk or side effect 1: Loss of webmail access for users. Mitigation is to provide clear communication and support for alternative email clients.
• Roll back: Step 1: Access the Woppoware PostMaster administration interface. Step 2: Locate the webmail service configuration settings. Step 3: Enable the webmail service. Step 4: Save changes and restart the service.

8. References and Resources

• Vendor advisory or bulletin: http://packetstormsecurity.nl/0505-exploits/postmaster.txt
• NVD or CVE entry: CVE-2005-1650